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Welcome again to our monthly newsletter with features on exciting celestial events, product reviews, tips & tricks, and a monthly sky calendar. We hope you enjoy it!
The planet Jupiter is just making its appearance in the evening skies, and now dominates the southern horizon most of the night. For anyone who follows Jupiter closely, the giant planet presents a rather different face in 2007 than we’ve seen in recent years.
Credit: D. L. Sharp
The two images above, made by D. L. Sharp with an 8-inch Newtonian, clearly show the changes which have taken place since this time last year.
All we ever see of Jupiter is the top of its thick gaseous atmosphere, and it’s easy to forget that what we are seeing is clouds and that, as on our own planet, cloud patterns can change.
In recent years, the most obvious features have been two dark belts, known as the North Equatorial Belt and the South Equatorial Belt, with a lighter zone, the Equatorial Zone, in between, marking the planet’s equator. Bright Tropical Zones appeared north and south of the two main belts. This is shown in the image on the left; north is at the top in these images. The result was a fairly symmetrical array of belts and zones relative to the equator.
Fast forward to 2007
The most striking change is that the southern half of the South Equatorial Belt has faded, changed from dark to light. At the same time, the normally bright Equatorial Zone has darkened, and the North Temperate Belt, to the north of the North Equatorial Belt has also darkened. The visual effect of this is that Jupiter’s cloud belts have become noticeably asymmetrical: the whole northern half of the planet having become one dark complex belt, and the whole south of the planet becoming a broad bright zone.
These changes in the background colors of the belts and zones have had a striking effect on the appearance of Jupiter’s famous Great Red Spot. In recent years, the GRS has been buried in the dark hued southern component of the South Equatorial Belt, making it difficult to see in small telescopes due to the lack of contrast. In some years, it has actually been lighter than its background Belt, and has been visible only as a brighter area in a dark Belt, known as the Red Spot Hollow.
But now, in 2007, it is immersed in a broad white zone, and stands out clearly from its background, as can be seen in the image at right above. As a result, the Great Red Spot is easier to see in a small telescope than it has been for many years.
On the night of 2007 June 17/18 I was able to see it readily with my 100mm Orion ED refractor at 180x, which was next to impossible last year. No color was visible; that requires a larger aperture: on June 9/10 it appeared a pale salmon pink in my 11-inch Newtonian.
You can use Starry Night® to predict when the Great Red Spot will be close to Jupiter’s central meridian, the imaginary north-south line though the center of Jupiter’s disk.
Starry Night® needs to know the current longitude of the Red Spot, since it drifts in longitude. It gets this information from a file in the Sky Data folder called JupiterGRS.txt. Mac users will need to control-click on their Starry Night® application icon, choose “Show Contents”, and then drill down through Contents, Resources, and Sky Data to find this file.
If you have Starry Night® 6.0.0 or earlier, this file should be edited to contain the value 118.0. If you have Starry Night® 6.0.1 or higher, it should be 284.0.
With these values in the JupiterGRS.txt file, Starry Night® will depict the position of the Great Red Spot accurately so that you will know when best to observe it. Because of its improved visibility this year, give it a try!
Although I have a fine Dobsonian reflector which I use for most of my observing, I’ve long been on the lookout for a “grab and go” scope: one which I could carry outside in a minute or two for a quick look, or put, more or less in one piece, in the back of my car to take to public or school star parties. I’ve bought a number of potential “grab and go” scopes over the years, but they’ve all failed to satisfy in various ways: too bulky, too little aperture, awkward to set up or use. Recently Celestron developed a new size of SCT, something that hasn’t happened for decades. I’d always found their 5” SCT didn’t have enough aperture for the planetary views I like, and their 8” was too bulky to be truly portable, so their new 6” (actually 150 mm) looked promising.
The 6” optical tube is available in two configurations: either on a CG-5GT Advanced Series German equatorial mount or on the single-arm altazimuth mount used for years on the 5” and 8” NexStars. I didn’t want the weight and complication of a German equatorial mount, so went for the NexStar version. The weight difference is very significant: 30 pounds for the NexStar version vs. 52 pounds for the AS-GT version! The NexStar version can easily be carried in one piece, and, if necessary, can be broken down into two or three major components for transport: tripod, mount, and optical tube. The most recent versions of the SE series use a standard Vixen/Synta dovetail system for attaching the tube to the mount, which is a nice bonus.
Assembly and set up
The telescope arrived well packed in a double walled cardboard box. Almost no assembly was required other than attaching the eyepiece tray to the tripod, bolting the telescope mount onto the tripod, attaching the finder, prism diagonal and eyepiece, and inserting eight AA batteries. I did notice some slight discoloration on the front of the corrector plate and some signs of black touch-up paint on the mount base. The red-dot finder required a shim under its base to make it parallel with the main optical axis, there not being enough travel in its adjustment screws.
My advance reading prepared me to know that the internal AA batteries would be barely adequate to power the scope and would require replacement virtually every night. Rather than buy the PowerTank external battery which Celestron sells, I opted for a simpler unit from my local automotive supply store. One problem I wasn’t prepared for is that Celestron uses an odd size of 12 volt connector with a 2.1 mm pin rather than the more common 2.3 mm pin. My scope behaved very erratically under external power until I replaced the connector from the battery pack.
The altazimuth mount is made out of heavy aluminum castings and has large bearing surfaces and gears, so is remarkably rugged. I had been a little dubious about the single-arm design, but in practice the mount is extremely solid and any vibration dies down within a second. I’m not sure how it would perform with an 8” optical tube, but it is definitely overbuilt for the 6” tube, which I like.
The mount is controlled by a hand controller which stores neatly in the upright arm. There are 19 buttons arranged in a mostly logical way:
Some keys do double duty, such as the “6” and “9” keys which allow you to scroll through lists of options (10). I found the keys too close together, especially when wearing gloves, and it was too easy for someone with large fingertips like myself to press the wrong key. In particular, I found it hard to maintain my orientation on the arrow keys by feel, and often pressed the Enter key instead of the up-arrow and the “2” key instead of the down arrow. I would prefer to have the scroll keys separated from the keypad, as these are used a great deal and are hard to locate by feel.
There is an RS232 serial port in the bottom of the hand controller (12) which allows for control of the telescope using Starry Night® Pro or Pro Plus software. I used a Starry Night® BlueStar for wireless telescope control.
Hand control operation
The current software in the hand control has what is the easiest alignment procedure available for totally inexperienced users: SkyAlign. The user enters their location, and the current time and date, and then points the telescope at any three bright objects in the sky. There is no need to know the names of the objects, or even whether they are stars or planets (or even the Moon). I found that, given a little care in centering each object, this system worked flawlessly, objects being placed in the low power field of view for hours on end. Most of the time I used a second alignment method, Auto Two-Star Align, which is slightly faster but requires that you know the names of some stars. It also was very accurate over an evening’s observations. There are several other alignment methods, but these two did the job for me. The built in catalogs cover most of the objects most people might want to see, and there is a 99-object user database for additional objects; I set this up for the variable stars I observe on a regular basis.
I had heard ahead of time that this scope had excellent optics, and this proved to be the case. Mechanically it is excellent, with no detectable image shift while focusing. Focusing was very smooth, and it was easy to achieve critical focus on the planets. Collimation was also excellent out of the box, requiring no touch up. I found that most evenings it took the scope about an hour to cool down to operating temperature, after which its images were excellent. This is typical of most Cassegrain scopes. My favorite test object, Jupiter, is painfully low in the sky this year, but even so I was able to see a satisfying amount of detail once the scope had reached operating temperature.
One problem I have always had with Schmidt-Cassegrain telescopes is their relatively long focal ratios, resulting in narrow fields of view. One of my first purchases was a 0.63x focal reducer/corrector. This screws onto the back of the scope between the scope and the 1.25” visual back, and converts the f/10 focal ratio (1500 mm focal length) to f/6.3 (945 mm focal length). This gives me a nice wide field with my Meade 24.5 mm Super Wide Angle eyepiece: 1.7 degrees field of view at 39x, excellent for all but the very largest deep sky objects. I like the effect of this reducer/corrector so much that I usually leave it in place for most of my observing, except for high power lunar and planetary observing with my Orion binoviewer.
The fun factor
One thing that may not be clear from my comments so far is that this telescope is really fun to use! Seeing it sitting by the door with its cheerful bright orange tube, it’s hard to resist carrying it outside just about any clear night. Once aligned, it’s easy to log a series of variable star observations, since it slews to the charted field quickly, quietly, and accurately. With the serious “work” done, it’s always tempting to launch the scope in tour mode and visit new and different objects. Under my dark country skies, its well coated optics give me bright images of many “faint fuzzies.” Before I know it, it’s long past midnight, my toes have turned to icicles, but I’m still bopping along from one object to the next. I used to be a stickler for star hopping, but I now find myself embracing GoTo, especially when it comes in such a friendly package as this one.
As I described last month, Venus and Saturn are rapidly approaching one another in the twilight sky. This is a reminder that they will be less than a degree apart on the evening of July 1, and will be a spectacular sight either with the naked eye or in a small telescope at low magnification.
You won’t believe until you see it how much larger and brighter Venus is than Saturn, both because of its closeness and its higher reflectivity. Don’t miss this!
Send us your original electronic images of solar system celestial objects—Planet, Moon, or Sun—captured with an Orion® StarShoot Solar System or Deep Space imaging camera, and you will be eligible to win one of three terrific prizes.
All images will be judged by Orion's panel of astrophotography experts, and three winners will be chosen. So fire up your StarShoot camera and take your shot!
Prizes to be Awarded
Deadline for image submission is July 31, 2007. Click here for full details.
Winners will be announced on or before August 31, 2007. Winning images will be showcased in the StarShoot Image Gallery at OrionTelescopes.com, and other submitted images of good quality will be posted in the Gallery.
For those of us in mid-northern latitudes, it's probably best to start low; the underbelly of Scorpius skirts the southern horizon, making observation tricky.
The Scorpius Jewel Box is actually two open clusters in close proximity: the top one loose, and the lower one tight. A great binocular target.
NGC 6242 is an open cluster, and NGC 6281 is an open cluster with nebulosity.
C69 or "The Bug Nebula" (aka NGC 6302) is an interesting planetary which looks, at first glance, like a galaxy. The western side of the nebula has a prominent lobe with a tapered end while the eastern side is noticeably blunt.
NGC 6383 is a dim, wide cluster with nebulosity.
M6 is a bright and obvious open cluster which makes for an easy binocular target. Telescopes show rich detail and M6 is seen to be aptly named, "The Butterfly Cluster".
Three globular clusters sit close to Antares. M4 and M80 are well known, but a challenge is NGC 6144 because it sits so close to the 1st Mag red supergiant.
Antares itself is 600 lightyears away and glows with a luminosity 12,000 times greater than our own sun.
This area rewards binocular users generously. There are seemingly endless textures, patterns, star clusters and odd little clouds, all of which are well within the grasp of even basic optical aids.
Phillip Holmes of Rockhampton, Australia took this photo of Rho Ophiuchus with his STL-11000M camera on a Televue NP101mm F/5.4 telescope. Exposure times 2x2 bin RGB 15min x 2 and Ha 1 x 120min and clear 1 x 115min. Darks, flats taken for all frames. Phillip writes: “the seeing was not that great and my focus is a tiny bit off.” Looks great to us.
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